Field of the Invention
The present invention relates to a planar light source combining a light guide plate and a light-emitting apparatus, wherein a light coming from the light-emitting apparatus is introduced into the light guide plate through a lateral surface of the light guide plate and is emitted from a top surface of the light guide plate. More particularly, the present invention resides in a light-emitting apparatus employing a Group III nitride semiconductor light-emitting device. The present invention also relates to a method for producing a Group III nitride semiconductor light-emitting device.
Background Art
A planar light source combining a light guide plate and a light-emitting apparatus has been widely known, for example, from Japanese Patent Application Laid-Open (kokai) No. 2008-108994. In such a light source, the light-emitting apparatus is disposed on a lateral surface of the light guide plate made of transparent resin such as acrylic resin, a light from the light-emitting apparatus is incident through the lateral surface of the light guide plate in the light guide plate, the light is reflected inside the light guide plate and is extracted from a top surface of the light guide plate so that light is emitted in a planar shape. Especially, a planar light source employing a blue light-emitting device made of Group III nitride semiconductor and a white light-emitting apparatus having a sealing resin containing fluorescent material sealing the light-emitting device, has often been employed in, for example, a backlight of a liquid crystal display.
On the other hand, Japanese Patent Application Laid-Open (kokai) 2008-124254 discloses a Group III nitride semiconductor light-emitting device having a quadrangle shape in a plan view, wherein long-side lateral surfaces are reversed tapered (the lateral surfaces are inclined such that the cross section area of a plane parallel to the substrate main surface increases as the distance from the substrate increases), and short-side lateral surfaces are perpendicular to the substrate main surface.
However, in the conventional planar light source combining the light guide plate and the light-emitting apparatus, the rate of light from the light-emitting apparatus taken inside the light guide plate is not sufficient. Accordingly, there remains room for further improvement in the light output from the planar light source.
There is no specific description about the orientation characteristics of the light-emitting device disclosed in Japanese Patent Application Laid-Open (kokai) 2008-124254. There is also no description of the structure of the planar light source combining the light-emitting apparatus employing these light-emitting devices and the light guide plate.